Lui is for male = him Lei is for female = her You can also use "lei" as "you" in formal conversations and with someone you are not on familiar terms with. :)

1) /lei/ refers to a woman, /lui/ refers to a man; this when they are pronoun of third singular person 2) when used as the formal expression that substitutes the /tu/, only /lei/ (or the now fading away /ella/, but still used in writing) may be used; the gender of the listener does not count in this case.